Answer:
4.457 × 10²⁴ molecules H₂S
General Formulas and Concepts:
Chemistry - Atomic Structure
Reading a Periodic TableUsing Dimensional AnalysisAvogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.Explanation:
Step 1: Define
252.3 g H₂S
Step 2: Identify Conversions
Avogadro's Number
Molar Mass of H - 1.01 g/mol
Molar Mass of S - 32.07 g/mol
Molar Mass of H₂S - 2(1.01) + 32.07 = 34.09 g/mol
Step 3: Convert
[tex]252.3 \ g \ H_2S(\frac{1 \ mol \ H_2S}{34.09 \ g \ H_2S} )(\frac{6.022 \cdot 10^{23} \ molecules \ H_2S}{1 \ mol \ H_2S} )[/tex] = 4.45688 × 10²⁴ molecules H₂S
Step 4: Check
We are given 4 sig figs. Follow sig fig rules and round.
4.45688 × 10²⁴ molecules H₂S ≈ 4.457 × 10²⁴ molecules H₂S
Answer:
[tex]\boxed {\boxed {\sf 4.457*10^{24} \ molecules \ H_2S}}[/tex]
Explanation:
First, find the molar mass of H₂S
Use the Periodic Table to find the mass of hydrogen and sulfur.
Hydrogen (H): 1.008 g/mol Sulfur (S): 32.07 g/molTo find the molar mass of H₂S, multiply the molar mass of the elements by the number of atoms of the element.
Hydrogen (2): (2)(1.008 g/mol) =2.016 g/molSulfur (1 atom): (1)(32.07 g/mol)= 32.07 g/molAdd.
2.016 g/mol + 32.07 g/mol =34.086 g/molNext, find the number of moles in the sample (252.3 g) Use the ratio of grams to moles.
[tex]252.3 / g * \frac{1 \ mol \ H_2S}{34.086 \ g }[/tex]
Multiply. The grams will cancel each other out.
[tex]\frac{252.3 / mol }{34.086 \ }=7.40186587 \ mol[/tex]
Finally, found the number of molecules using Avogadro's number (There are 6.022*10²³ molecules in 1 mole).
[tex]7.40186587 \ mol \ H_2S*\frac{6.022*10^{23} molecules \ H_2S}{1 \ mol \ H_2S}[/tex]
Multiply. The mole (mol) will cancel each other out.
[tex]7.40186587*{6.022*10^{23}\ molecules \ H_2S} = 4.45740363 *10^{24} \ molecules \ H_2S[/tex]
Round to the correct number of significant figures. The sample had 4 sig figs (2, 5, 2, 3), so round to 4 sig figs.
[tex]4.457*10^{24} \ molecules \ H_2S[/tex]
There are about 4.457 * 10²⁴ molecules of H₂S